The present invention relates to plastic wheels and, in particular, to a blow molded wheel having a spring biased axle retainer.
Varieties of pneumatic and composite wheels have been developed that include integral axle retainers. Some available composite wheels include an injection-molded hub that supports a molded rubber tread piece at a flanged rim. The tread piece is separately attached to the hub, such as by stretching. A spring-biased pin is molded into the hub and the pin projects into the bore of an axle support. With the attachment of the wheel to an axle having a mating annular recess, the pin depresses and expands into the recess to permanently secure the wheel to the axle. The pin otherwise is not exposed to facilitate detachment of the wheel.
An all plastic wheel can provide a cost-effective alternative. However, all plastic wheels are generally not available that include an integral retainer. A blow-molded wheel that does include a retainer is shown at U.S. Pat. No. 5,368,371. The retainer consists of annular tabs that extend into an axle bore and that mount to a grooved recess at a mating axle. The strength of the tabs can limit the type of applications to which such wheels are placed. The tabs are also prone to damage, if the wheels are removed.
The present invention was developed to provide an improved blow-molded plastic wheel having an integral axle retainer. The wheel provides an externally accessible, spring biased pin retainer that is inserted into a blow-molded wheel. The wheel includes a tread surface that can be molded as part of the wheel or that can be separately attached to the wheel. A spring biased pin radially projects from a pin retainer sleeve that is fitted to an axle sleeve. The axle sleeve provides a load bearing surface for the axle.
It is accordingly a primary object of the invention to provide a blow molded wheel with an integral axle retainer.
It is a further object of the invention to provide a wheel having an axle retainer that indexes to a separately molded wheel and includes a pin and axle sleeve that extend transverse to one another.
It is a further object of the invention to provide a wheel with an axle retainer pin that can be released from the axle after mounting.
It is a further object of the invention to provide a retainer that can be mounted to the wheel prior to final cure.
Various of the foregoing objects, advantages and distinctions of the invention are obtained in a presently preferred blow-molded wheel. The wheel is blow molded in conventional fashion and includes a cavity at one of the spokes that is shaped to accept a spring biased retainer. The cavity opens to an axle bore at the wheel. The retainer is set into the cavity immediately upon the wheel being withdrawn from the mold, while the plastic is warm. The plastic shrinks around the retainer as it cools and permanently secures the retainer to the wheel.
The retainer includes a pin sleeve that supports a spring within a longitudinal bore. The spring biases the retainer pin to project into a longitudinal bore of an axle sleeve. The axle sleeve concentrically mounts within the axle bore. The bore of the axle sleeve acts as a bushing and provides a load bearing surface for the axle. The bore of the axle sleeve extends transverse to the bore of the pin sleeve. An opening is provided through the walls of the pin sleeve to permit release of the pin from the axle.
Still other objects, advantages, distinctions and constructions of the invention will become more apparent from the following description with respect to the appended drawings. Similar components and assemblies are referred to in the various drawings with similar alphanumeric reference characters. The description should not be literally construed in limitation of the invention. Rather, the invention should be interpreted within the broad scope of the further appended claims.